the 7 is a nice camera isnt it, I was sorely tempted to get one at one pt, but alas, never did. As you know, if you take it, dont screw around with water protection, your shot rolls will not be happy (nor you) if the paper gets wet. God, when I think of the all the B+W 120 film I have developed over 20 years...
Some years ago a photog I know travelled in China with a 7, did his own scans on a Nikon scanner 8000 I think, and the show he did with the 3-4 ft wide prints were really really nice.
all the best with it, there are some really nice seat post bags outs there. Check out the poster Asana, he has used this stuff a lot too.
oh, and as you say, Im not sure I would take a rangefinder on a bike, ive shot with M bodies and even they can get out of whack and so if you do, you would want to be able to do the adjustment yourself. I never learned how to do it with Ms, but if I was doing something like you were doing, I would definitly get a tech to show you how to do it properly--can you imagine the feeling if after developing you see your focus is out********** Btw, what body are you thinking of taking instead, 35mm I presume? Ive worked in photo since 89 and while I havent shot film since the D100 ('02-03??) I been at it since the late 70s.
*you know, thinking about it, if you can safely and gently take the 7, the quality and more thoughtful approach to shooting would be worth it---I just wouldnt put it in a bike mounted bag-vibrations, i would be inclined to have it on my body, it would be treated to a lot less shaking etc. Id go with my instincts on that one, vibrations arent great for a real camera, and Ive seen screws come loose on Hasseblads etc, so I dunno....if it was me, id want to super protect it from vibrations....
good luck with your wacky bike project!